In well drilling operations, shale containing formations are sometimes encountered in which conventional aqueous drilling muds are difficult or impossible to use because the aqueous portion of the drilling mud reacts with clays in the shale to cause shale erosion, caving, and extrusion into the well bore. In extreme occurrences, the shale extrudes into the drilled borehole and presses against the drill string, making drilling difficult or impossible. Various methods, including air drilling, wax emulsion drilling, and the use of oil-based drilling fluids, have been used to counteract the problem. There is, however, need for an aqueous drilling fluid useful in drilling through such unstable shales.